The field of the invention is in the art of solar cells and particularly vertical multijunction solar cells.
Vertical multijunction solar cells are well known. Their enhanced radiation resistance is well recognized, however, the present state of the art cells generally have a poor conversion efficiency because of an inherently high series resistance factor associated with their structural configuration. This results from a relatively long path length that the charges have to travel in order to reach a grid finger. In addition the present state of the art structures have a mechanical fragility resulting from a tendency of these cells to fracture along any one of the channels when structural stresses are applied to the cell, as when handling and mounting the cell as well as from shocks, vibration, and structural stresses encountered by the cells during launch and in transportation.
Typical examples of the prior art are exemplified by U.S. Pat. No. 3,690,953 to patentee J. F. Wise, and the following published papers: W. P. Rahilly, "Vertical Multijunction Solar Cells," Conf. Record of the Ninth IEEE Photovoltaic Specialists Conference, May 1972, page 44; P. Stella and A. Gover, "Vertical Multijunction Solar Cell," Conf. Record of the Ninth IEEE Photovoltaic Specialists Conference, May 1972, page 85; and R. K. Smeltzer, D. L. Kendall, and G. L. Varnell, "Vertical Multijunction Solar Cell Fabrication," Conf. Record of the Tenth IEEE Photovoltaic Specialists Conf., November 1973, page 194.